1. Field of the Invention
The present invention relates to an oscillating sprinkler for use in irrigating lawns, flowers, shrubs and the like, and more particularly to an oscillating sprinkler with a toggle valve.
2. Description of the Related Art
Oscillating sprinklers have long been known and used in the irrigation art for watering lawns, gardens, shrubs, flowers and other plants. Typically, such sprinklers include a water-driven motor mounted in a housing and which drives an elongated spray tube for side-to-side oscillation about a generally horizontal axis.
FIG. 6 illustrates a conventional oscillating sprinkler which includes generally a spray bar (not shown) and an impeller assembly 9 which is driven by the flow of incoming water to the sprinkler and drives the spray bar for oscillating movement. The impeller assembly 9 includes an impeller (not shown) and a reduction gear train 97. The incoming water flow drives the impeller which, through the reduction gear train 97, applies an oscillating motion to the spray bar which has nozzles from which the water is delivered. Specifically, water entering the impeller assembly 9 of the sprinkler passes into a central tube 99 and then into an inlet chamber 95 in the impeller assembly 9 where it passes into one or other of two impeller inlets 91, 92, depending on the condition of a toggle valve 96.
The toggle valve 96 has a rocker member 93 from which projects a lever surrounded by a helical spring 94. The lever is extended to form a switching arm 98. By pushing the arm 98 in one direction the rocker member 93 is moved to the position illustrated in FIG. 6 in which the inlet 91 is open to enable water to enter the inlet 91 whilst the inlet 92 is blocked by the member 93. On the contrary, when the arm 98 is pushed in the opposite direction, the rocker member 93 moves over center to the alternative (non-illustrated) position, in which the inlet 92 is open for the passage of water and the inlet 91 is closed. Movement of the arm 98 is affected by two sweep setting rings (not shown) mounted for independent rotational adjusting movement about the central longitudinal axis of the sprinkler. Each ring has a radial wall provided with an arcuate slot through which the aim 98 extends, and the edge of each slot is capable of being engaged by the arm 98 to cause change-over of the rocker member 93.
When water reaches the impeller through the inlet 91, the water flow drives the impeller in one rotational direction and when water reaches the impeller through the inlet 92 the water flow drives the impeller in the other rotational direction. The impeller is linked to the gear train 97, the result being that the whole of the impeller assembly 9 and the spray bar oscillate, about a stationary gear (not shown) carried by the central tube 99, through an angular displacement determined by the setting of the sweep setting rings.
In this sprinkler, the movement of the rocker member 93 is affected by the helical spring 94 and the switching arm 98. When the arm 98 is pushed, a torque is built on the spring 94 to have the rocker member 93 switched. However, when the water pressure is high, the torque produced by the spring may not be easily concentrated or dispersed to switch the rocker member 93, which may finally cause a failure of the toggle valve 96.